JPS60261015A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a high-density magnetic recording medium which obviates the generation of static electricity and has excellent running stability and S/N by providing a vapor deposition layer having an earthworm-shaped build-up structure formed with many microprojections on the surface of a high-polymer substrate on the side opposite from the surface on which a thin ferromagnetic metallic film is formed. CONSTITUTION:A magnetic recording layer 7 consisting of the thin ferromagnetic metallic film is formed on one surface of the high-polymer substrate 6 consisting of polyethylene terephthalate, etc. A resin such as polyester or polyamide incorporated therein with fine org. particles of polyimide, etc. or fine inorg. particles of silica, titania, etc. as a filler 9 is coated on the opposite side face of the substrate 6. A resin layer 8 having the earthwormshaped build-up parts 11 and trough parts 12 shown by diagonal lines is formed by subjecting the resin to stretching, etc. after coating. The vapor deposition layer 10 consisting of a partially oxidized film, oxide film, partial nitride, etc. is formed by vacuum deposition on the layer 8. The build-up parts 11 are preferably formed to about 200Angstrom height, average 500mu length and about 0.3mu width. The magnetic recording medium which does not generate static electricity, has good running stability, has low noise and does not increase noise even after repeated use is thus obtd.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a magnetic recording medium suitable for short wavelength recording.

Conventional Structures and Their Problems In recent years, in order to further increase the density of magnetic recording, consideration has been given to the practical use of new magnetic recording media in which a ferromagnetic metal thin film is used as a magnetic recording layer.

High-density magnetic recording is achieved by shortening the wavelength and narrowing the track, but when the wavelength is shortened, spacing loss dominates the loss, so the surface of the magnetic recording layer is smoothed. For this reason, efforts have been made to reduce the tape tension in the tape transport system for recording and playback to ensure smooth running, and to increase the number of rotating parts. , magnetic recording media are also susceptible to the effects of static electricity, so measures are being taken for magnetic recording media as well.

An example of this is shown in FIG. 1, which is an enlarged cross-sectional view of a magnetic recording medium.

In Figure 1, 1 is a polymer substrate, 2 is a ferromagnetic metal thin film, 3 is a filler, 4 is a resin, and 6 is 3, 4 (or other additives (added depending on the purpose, but not shown)) ).

Static electricity can be countered by using a conductive filler at 3 in Figure 1, but a certain amount of filler is required, and even if a filler with a small diameter is selected,
Agglomeration is unavoidable, resulting in poor surface properties and increased noise. Since it is difficult to balance static electricity countermeasures with this noise, improvements have been desired.

OBJECTS OF THE INVENTION The present invention was made in view of the above circumstances, and it is an object of the present invention to provide a magnetic recording medium with little noise and stable running.

Structure of the Invention The magnetic recording medium of the present invention has a surface opposite to the magnetic recording layer,
It is characterized by being composed of a vapor deposited layer having a worm-like raised structure with minute protrusions, and has low noise and stable running.

Description of examples Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is an enlarged sectional view of the magnetic recording medium of the present invention. FIG. 3 is a schematic top view of the back coat layer of the present invention.

In FIG. 2, 6 is a polymer substrate, 7 is a magnetic recording layer, 8 is a resin, 9 is a filler, and 10 is a vapor deposition layer.

In FIG. 3, the non-hatched portion is the earthworm-like raised portion 11 of the resin layer 8, and the hatched portion is tentatively referred to as the trough portion 12 herein.

The distribution state of the filler 9 is not shown here, but whether to place it mainly in the valleys 12, in the raised areas 11, or randomly is a design issue and can be devised as appropriate. .

The polymer substrate that can be used in the present invention is a film-like substrate made of polyester such as polyethylene terephthalate, toimide, polyimide, polyether sulfone, etc. and having a thickness of 16 μm to 3 μm.

In order to obtain worm-like protuberances as shown in FIG. 3, there are two methods: coating a resin such as polyester, polyamide, polyimide, polycarbonate, etc., and stretching after coating.

At that time, organic and inorganic fillers can be selected singly or in combination, but the degree of dispersion of these fillers into the resin can be adjusted to disperse powder as appropriate to form oil ridges and microprotrusions. form a composite surface.

On top of this, a partial oxide film, an oxide film and a two-part nitride film, etc., are deposited to a thickness of 300 to 300 mm by vacuum evaporation.

Preferably, a vapor deposition layer of 500 to 1500 is formed.

This vapor-deposited layer acts like a conductive layer when used as a magnetic tape, and due to the shape effect mentioned above, the actual contact area is small, so the frictional resistance is low, the generation of static electricity is negligible, and safe running is ensured. Can be secured.

Further, unlike the conventional example in which conductivity is provided by the amount of filler, the amount of filler can be reduced, so that no increase in noise due to deterioration of surface properties occurs.

Although the mechanism that causes the difference between the present invention and a surface formed by only bumps or only particles has not been fully elucidated, the mechanism that causes the difference between the surface formed by protrusions and the present invention has not been sufficiently elucidated. Although this is not the case, it is presumed that the durability of the surface, ie, the surface shape, is maintained by the combined action of the protrusions and bulges, ie, by the action of the raised layer and irrigation.

Incidentally, the term "deposited layer" is a general term for a thin film formation method represented by vacuum evaporation, and includes other methods such as ion blating, electric field evaporation,
Of course, a method such as sputtering may also be used.

It should be noted that the provision of a lubricant or the like on the surface may be done as necessary and is within the scope of the present invention.

The magnetic recording layer of the present invention does not depend on the direction of the axis of easy magnetization, and includes a laminated structure with thin films other than ferromagnetic metal thin films.

One embodiment will be described in more detail below.

〔Example〕

A polyethylene terephthalate substrate having a thickness of 10 μm was provided with earthworm-like protuberances to a height of about 200 mm on one side, and a combination of earthworm-like protuberances and microprotrusions was provided on the other side, and a vapor deposition layer was provided thereon.

Further, as a magnetic recording layer, a partially oxidized Co film was formed along a cylindrical can having a diameter of 60 (7) by a continuous incident angle variation vapor deposition method.

The Co film has a thickness of 15,000 mm and a coercive force of 900 mm (according to Oersted).

The vapor deposited film on the side opposite to the magnetic recording layer was a 7'H1TiN, TiC film obtained by high-frequency dipole sputtering.

The degree of vacuum during sputtering is argon partial pressure 7
It was controlled in a mixed atmosphere of 10 Torr and oxygen partial pressure IX10-3 Torr.゛The earthworm-like protuberances were formed from polyester resin.

The conditions and the results of the tape evaluation are summarized in the table below.

In the tape evaluation, running stability was determined by visually inspecting the image for shake, and if it was good and could not be visually determined, it was rated B if it was noticed on the A1 screen. (The initial value of the tape flatness 7 was set to o [dB].) The noise was 4 t, and the total of 4 corresponded to a wavelength of 0.66 μm.

A comparison tape was investigated using a resin layer containing carbon as a filler.

The test machine used for the evaluation was a commercially available video tape recorder modified to half speed and equipped with a variable tension mechanism.

The earthworm-like ridges are mountain-like ridges extending in the longitudinal direction of the tape, and the average length of the longitudinal sides is 500 μm, the width direction is 0.3 μm, and the pitch in the width direction is unified to an average of 2 μm.

As is clear from the table, compared to the conventional example, the product of the present invention has
The noise is low and remains stable even when used repeatedly.
Running stability is also good.

The present invention has confirmed that the same degree of improvement, that is, an improvement of more than sdB in noise level, is achieved with other material combinations.

Effects of the Invention The magnetic recording medium of the present invention does not generate static electricity and can run stably by disposing a vapor deposited layer having earthworm-like protuberances with minute protrusions on the side opposite to the ferromagnetic metal thin film. In addition, the initial noise is low and does not increase even after repeated actual use.

According to the present invention, it can be realized with performance expected for practical application of high-density recording, and its practical value is great.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a conventional magnetic recording medium, FIG. 2 is an enlarged sectional view of the magnetic recording medium of the present invention, and FIG. 3 is an explanatory diagram of the worm-like raised state of the present invention. 8 Bemiz-like protuberance, 9... minute protrusion, 10
・・・・・・Vapour-deposited layer.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a ferromagnetic metal thin film as a magnetic recording layer, and a polymer substrate on the opposite side to the side on which the magnetic recording layer is disposed is a vapor deposited layer having a worm-like raised structure having microprotrusions.